Propeller governor tester



Oct. 29, 1946.

I. v. FALK 2,410,155 PROPELLER GOVERNOR TES TER Filed May 15, 1,944 2 Shets-Sheet '1 INVENTOR. fimVV/ihx,

BY- Ma= Patented Oct. 29, 1946 PROPELLER GOVERNOR TESTER Irvin V. Falk, Union, N. J., assignor to Reeves Pulley Company, Columbus, Ind., a corporation of Indiana Application May 15, 1944, Serial No. 535,693

The present invention relates to a propeller governor tester, and is disclosed in connection with a commercial governor designed to adjust the pitch of an airplane propeller to optimum positions for varying, conditions of aircraft operation. The governor disclosed is of a type which, in response to variations in engine speed, controls the rate and direction of flow of fluid (oil, in this case) to a piston connected to adjust the propeller pitch, so that an increase in engine speed will result in an increase in the bite of the propeller, thus increasing the load 'on the engine to retard the engine; and vice governor mechanism to vary the rate at which the governor mechanism is driven in response to the demands of that mechanism. A further object of the invention is to provide a test stand of the character described which shall be highly flexible, so that it may be adapted to the testing.

of various forms of governor mechanisms.

To the accomplishment of the above and related objects, my invention may be embodied in the form illustrated in the accompanying drawings, attention being called to the fact, however, that the drawings are illustrative only, and that changes may be made in the specific construction illustrated and described, so long as the scope of the appended claims is not violated.

Fig. "1 is a diagrammatic illustration of my test stand with a commercial governor mechanism associated therewith, parts being broken away or shown in section for clarity of illustration;

' Fig. 2 is an enlargedsection through a detail of the test stand mechanism; and

Figs. 3 and 4 are sectional views of a governor mechanism in various positions of adjustment. In- Fig. 1, the reference numeral It] indicates generally a commercial form of governor mechanism primarily constructed for the automatic control of controllable pitch aircraft propellers. The governor mechanism is illustrated, in Fig. 1, in under-speed position. In Figs. 3 and 4, the mechanism is illustrated in, respectively, onspeed and over-speed.positions.

The selected governor mechanism comprises a rotor ll carrying centrifugal fly weights [2, i2,

14 Claims. (Cl. 731) 2 each provided with a finger underlying a disc l3 (see Fig. 3) at the upper end of a reciprocable valve body I4 which is urged, by a spring I5, toward the position illustrated in Fig. 1. A plunger l6 constitutes an abutment for the upper end of spring l5, and said plunger is provided with rack teeth I! meshing with a pinion l8 adapted to be adjusted by manipulation of a hand wheel, or the like, I9, (Fig. 1) whereby to adjust the position of the plunger l6 and the degree of pressure exerted by the spring I5 upon the disc l3. It will be obvious that such adjustment of the plunger 16 will vary the speed of the rotor H at which the flyweights l2 will assume the on-speed position of Fig, 3.

The governor mechanism includes a gear typ pump 29 adapted to discharge fluid through a passage 2| to a passage 22, one end of which communicates, through a valve 23 biased to closed position by a spring 24, with a passage 25 for a purpose later to be described. 1

The valve I4 is reciprocably mountedin a bore 26; and, near its upper end, said valve is formed with a port 21 adapted, under underspeed conditions, to register with a passage 28. The port 21 communicates with a bore 29 which opens into the bore :26. The valve body His further formed, intermediate its ends, with a reduced section 30, providing a circumferential space which, in the over-speed position of Fig. 4, establishes communication between the passage 22 and the passage 28.

In the position of Fig. 3, all flow passages are sealed from each other, except that the pressure produced by the operation of the pump 20 will depress the valv 23 against the tendency ofthe spring 24, thus moving the valve23 to the position illustrated in Fig. 3, to establish a flow circuit from the pump outlet 2! through passage 22, valve 23, and passage 25, back to the pump inlet 91.

In the under-speed position of Fig. 1,-the port 2'! registers with the passage 28 to permit fluid to flow from said passage 28 through the port 2'! and bore 29 to the bore 26. In the overspeed position of Fig. 4, a flow path is established from the pump outlet 2| through the passage .22, past the reduced section 30 of the valve l4, and. to the passage 28. The effect'of these various positions upon the parts of the test stand, and the results thereof upon the parts of the governor mechanism will become apparent as the description proceeds.

The test stand includes an electric motor 3| upon the spindle 32 of which ismounted a varid sc 53 toward the disc 53. diameter of the pulley 33 is reduced, the effective able-effective-diameter pulley, indicated generally by the reference numeral 33. Said pulley comprises a coned disc 34 fixed to the spindle 32, and a mating coned disc 35 axially sh table relative to said spindle 32. The shifting mechanism for said disc 35 comprises a thrust bearing 35 to which is operatively connected a yoke 3i adjustably mounted upon a stem 38 reciprocably carried in a guide sleeve '39. A lever iii is pivotally mounted at M upon a bracket carried by said guide sleeve 39, and is operatively connected to cause reciprocation of the stem 38 in response to oscillation of said lever it. The lever it carries a pair of pins 42 and 43 diametrically opposed with respect to the fulcrum 4| for the lever 4 and a cooperating lever 44 is provided with ears 45 and 1-5 respectively supported upon said pins 42 and 43. The lever 44 may preferably take the form of a yoke straddling the lever ill, and provided on both sides of said lever M] with cars 45 and 46 cooperating with opposite projections of the pins 42 and 43. A spring M, hooked over pins 48 and 49 upon the levers MI and a l, respectively, normally holds both ears of the lever t l incontact with the pins 52 and 43; but if a force 'ten'ds to move the lever 44 beyond either limiting position of the lever All, the lever is will simply pivot about one 'or the other of the pins 52 and t5, thus stretching the spring 41. Upon relaxation of the force applied to the lever 44, the spring M will return said lever 44 to its illustrated position with respect to the lever 40;

A bar 50, comprising an extension of the lever 54, is formed to provide a portion bent downwardly in the manner illustrated for a purpose la-terto become apparent.

:Suitably 'journalled in parallelism with the jmotor spindle 32 is a driven shaft 55 carrying a variableeffective-diameter pulley indicated generally by the reference numeral 52 and comprising a coned disc-53 fixed to the shaft 5! and a mating coned disc 54 axially shiftable with respect thereto. A coiled spring 55 sleeved on the shaft 5| bears at one end againstthe disc 5 and at its opposite end against a fixed abutment 56 tending constantly to urge the disc 54 toward the disc 53. An edge-active belt 57 provides a j driving connection between the pulleys '33 and 52. 'It will be clear that, as the disc 35 is moved toward the disc 34, the belt 51 will be squeezed outwardly between the two d scs, thereby increasing the effective driving diameter of the pulley '33. correspondingly, the belt 51 Will be drawn inwardly between the discs 53 and 54. thus forcing the disc 54. to move, against the tendency of the spring 55, away from the disc 53, thus decreasing the effective d ameter of the pulley 52, to in- "crease the output speed of the shaft 55.

Similarly. when the disc '35 is moved away from the d sc 34, the tension upon the belt 5'! is relaxed, whereby the spring 55 is permitted to force the Thus the effective Y for a block 69, fixed to the driven shaft 55, and I provided with a socket 5! formed to provide a driv n seat for a bevel gear 52 at the end of the e gerating shaft' iiii for the governor mechanism As is well unders ood in the art. the shaft 63 is connected to drive the overnor pump 2% and the governor rotor I I. The details of this drive are immaterial to the present inven a flexible section ll. through a four-way valve 12 to conduits con- 4 and are well known in the art, an example being shown in the patent to E. Martin, No. 2,264,089, issued November 25, 1941; and therefore such details are not specifically disclosed herein. Suffice it to say that, in view of the illustrated connection, it will be clear that the pump 20 and the rotor ll of the governor mechanism iii will be driven at varying speeds corresponding to the speeds of the shaft 5! resulting from adjustments of the lever ill to shift the disc 35.

The test stand includes an oil reservoir 64% from which leads a supply pipe 65 connected to the inletof a gear type pump 66 driven by the shaft extension 6'! of the motor 3%. From the outlet of the pump 56 leads a short pipe section 68 communicating with a pressure regulating device 69.

The pressure regulating device 59 is preferably constructed to maintain a constant fluid pressure of, say, one hundred pounds per square inch in the supply conduit ill, in which is connected The conduit iii leads nected with the opposite ends of a fluid motor, indicated generally by the reference numeral '54.

The motor it comprises a cylinder iii, pivotally supported at Hil upon a bracket iii which may be supported'upon the base which mounts the motor '38. Reciprocably mounted within the cylinder i5 is a piston l6 having a stem ll projecting from the end of the cylinder [5 remote from the pivotal mounting MB. A conduit 13 com- 'municates with the lower end of the cylinder i5 and a conduit 18 communicates with the upper end thereof.

The four-way valve '52 is illustrated in detail in Fig.2. Its function is to connect the opposite ends of the cylinder l5 alternatively with the supply line it. Said valve comprises a casing 79 within which is mounteda valve body 88 formed with two straight-through passages 89 and 32, and with crossed passages 83 and 8 5. In the illustrated position, it will be seen that the passage 83 connects the conduit 13, communicating with the lower end of the cylinder '55, with the conduit 85, while the passage fi l connects the supply line ill with the conduit l8 communicating with the upper end of the cylinder. The valve body 82'!- is provided with a stem projecting from the housing iii; and an actuating lever Bl,

suitably pivotally mounted, as at 853, has a lost motion connection 89 with said stem E35. Clockwise movement of the lever Bl will shift the valve body 8% to its opposite position, in which the passage 8'! will establish communication between the supply line it and the conduit l3 leading to the lower end of the cylinder l5,while the passage 82 will connect the conduit 18 leading from the upper end of the cylinder Li with the conduit 8'5.

When the test stand is being used to test a governor-of the character illustrated'herein, the valve 12 will always be maintained either in the position illustrated in'Fig. 2, or, under special circumstances, in its intermediate position in which the supply line IE3 and the conduit 85 are entirely disconnected from the fluid motor E4. The opposite position of the valve 12 is for use in connection with a different type of governor mechanism,

The conduit '85 is provided with a flexible section 98, and leads to a passage 9! in the pillow bloc-k 58 which, when the governor mechanism illustrated herein is in position for test, registers when the fluid pressure'therein materiallyexceeds the above-mentioned predetermined value of,'say, one hundred pounds per square inch, flow is permitted through said regulating device and the conduit 92 to the reservoir 64. a

A further conduit 95 leads from the T-fitting 93 to a passage 95 in the pillow block 59 which, when the governor mechanism illustrated herein is in position for test, registers with the passage 25 of said governor mechanism. The pillow block is further formed with a bore 98 into which opens the bore 26 of the governor mechanism, and from which leads a passage 99 with which is connected a conduit I leading to the reservoir94.

' The conduit 73 has a branch -|0I and the conduit '78 has a branch I02, which branches lead through a four-way valve I03'similar to the valve 12. From said valve I03 are extended a conduit I05 leading to the delivery side of the pump 66, and a conduit I06 leading to the reservoir 64'.

In the illustrated position of the actuating lever be supplied to the upper end of the cylinder andthe lower end of said cylinder will be connected to the reservoir 64. Thus, the piston 16 will be moved downwardly in the cylinder I5 to shift the disc 35 toward the disc 34, thus increasing the speed of the shaft5 I. In the opposite extreme position of the lever I04, the branch I 0| will beconnected to the conduit I95 while the branch I02'is connected to the conduit I06,

whereby fluid under pressure will be supplied to the lower end of the cylinder 15, the upper end of said cylinder will be vented, 'andthe disc 35 will be moved away from the disc 34 to reduce the speed of the shaft 5|. Of course, during any such preliminary adjustment of the mechanism the lever 8! will be in its intermediate position,

locking the fluid motor 14 against any influence under the control of the governor mechanism I0.

The piston 16 is'connected to shift the disc 35 by means of a link I01 pivotally connected at I08 to the piston stem I1 and adapted to embrace the lever 50, being secured thereto by set screws I09.

Because of the pivotal mounting of the'cylinder -'I5 at II9, it will be clear that the yoke I01 may be secured to the lever 50 at any one of a plurality of points differently spaced from the pivotal axis '4I of said lever, Thereby, the volume of fluid required to be delivered to the fluid motor 14 in order to effect a given degree of adjustment of the disc 35 may be varied to flt desired operating conditions.

When a governor mechanism to be tested has been suitably associated with the'pillow block-59, the lever 87 being in its intermediate position, the motor 3| is energized, and the position of-the piston I6 and lever 40 will be adjusted, by manipulation of the lever I04, to bring the governor parts into the position of Fig. 3. The positions of the parts under these conditions of equilibrium are now noted, and then the lever I04 is further manipulated to reduce the speed of the shaft 5| to a value approximately 600 R. P. M lower than the equilibrium value. Now the lever I04 is set in its intermediate position and the lever '81 is set in the position illustrated in Fig. 1. Because :of the lower speed, the governor parts will now assume the positionsillustrated in Fig, 1.

'28, port 21, bore 29, bore 26, sump 98, passage 99, and conduit I 00 to the reservoir 64. Fluid under the pressure of the pump 65 is therefore supplied, through the conduit 68, regulator mechanism 69, conduit 10, passage 84, and conduit I8, to. the upper end of the cylinder I5 to move the piston I5 downward, thus swinging the lever 44 and the lever 40 in a counter clockwise direction to shift the disc 35 toward the disc 34 to increase the speed of the shaft 5| and of the governor mechanism. As speed of the governor mechanism is increased, it ultimately reaches a value at which the fly weights I2 will assume the positions iluustrated in Fig. 3, at which instant communication between the passage 28 and the bore 29 is cut off so that further flow of fluid from the lower end of the cylinder I5 is prevented. This is the condition of equilibrium which will'be maintained by the mechanism unless some further extraneous adjustment is made.

The speed of the shaft 5| may be further increased either by manipulation of the lever I04 or by manipulation of the hand wheel I9. If the adjustment is made by manipulation of the lever I04, such increase in the speed of the shaft 5| will cause the fly weights to move toward the position illustrated in Fig. 4, thus further lifting the valve I4 to establish communication between the outlet 2| of the pump 20 and the passage 28.

The fluid pressure produced by the pump 20 is considerably higher than that produced by the pump 66. Consequently, whenthe valve I4 assumes the position of Fig. 4, fluid will flow from the pump 20 throughthe passages 2| and 22,; around the reduced section of the valve I 4, and

valve at the right end thereof is set, and that valve will open to permit flow of fluid through the conduit 92, the fitting 93, and conduit 94 to the reservoir 54. Of course, the fluid driven by the pump 29 will be drawn thereto either from the reservoir (54 or from the conduit 92through the T-fitting93, conduit 95, and passages 96-, 25, and 91.

Such upward movement of the piston IE will shift the disc away from the disc 34 to reduce the speed of the shaft 5|, thus returning that speed to the value at which the fly weights I2 will assume the position illustrated in Fig. 3 in which the valve I4 cuts ofi communication between the pump outlet 2| and the passage 28.

If, instead of manipulating the valve 404, the operator shifts the hand wheel I 9 to increase the compression of the spring I5, the fly weights I2,

[at a given speed of the rotor II, will be swung first above described will be followed to increase a new value of governor mechanisms of the type ghereunder consideration is the'time required for the governor to pass a sufficient volume of fluid to bring the governor speed from a value 600 R. P. M. below that time interval without modifying the construction or connections of the governor mechanism. If the link Hl'l is shifted to a position farther from the axis of oscillation of the lever 49, ,a greater degree of movement of the piston 16 will be required to effect a given degree of movement of the disc 35. Thus, by so shifting the position of the link fill, the volume of fluid required to be passed by the governor mechanism to produce a speed increase of 600 R. P. M., and therefore the time interval required to produce that speed increase, can be materially enlarged.

I claim as my invention:

1. For use with a governor including a fluid pump, a rotor, means connected to drive said pump and said rotor, speed-responsive means operatively associated with said rotor and connected to shift avalve oppositely, in response to opposite variations in the speed of said rotor, between a high-speed position and a low-speed position through an intermediate position; testing apparatus comprising a source of fluid under constant pressure, a fluid motor including a cylinder and a piston reciprocable therein, conduit means connecting said fluid source with said cylinder on one side of said piston, conduit means connecting said cylinder on'the other side of said piston with said valve, passages controlled by said valve for alternatively placing said last-named conduit means in communication with said pump or with exhaust, a shaft connected to drive said pump and said rotor, and means for driving said shaft at variable speeds, said last-named means including an element sh-i-ftable oppositely to vary oppositely the speed of said shaft, and said fluid motor being connected to shift saidshiftab'le element,

2. For use with a governor including a fluid pump, a rotor, means connected to drive said pump and said rotor, speed-responsive means operatively associated with said rotor and connected to shift a valve oppositely, in response to opposite variations in the speed of said rotor, between a high-speed position and a low-speed position through an intermediate position; testing apparatu comprising a source of fluid under constant pressure, a fluid motor including a cylinder and. a piston reciprocable therein, conduit means connecting said fluid source with said cylinder on one side of said piston, conduit means connecting said cylinder on the other side of said piston with said valve, passages controlled by said valve for placing said last-named conduit means in communication with said pump when said valve is in its high-speed position and for placing said lastnamed conduit means in communication with exhaust when said valve is in its low-speed position, said valve closing said last-named conduit means when in intermediate position, a shaft connected to drive said pump and said rotor, and means for driving said shaft at variable speeds, said lastnamed means including an element shifta'ble oppositely to vary oppositely the speed of said shaft, and said fluid motor being connected to shift said shiftable element.

3. In a test stand, a fluid pump having an inlet and an outlet, a fluid motor comprising a cylinder and a piston reciprocable therein, a fluid reservoir, conduit means connecting said reservoir withsaid inlet, conduit means connecting said outlet with one end of said cylinder, pressureregulating means in said last-named conduit means for maintaining substantially constant the pressure in such conduit means, conduit means communicating with the opposite end of said cylinder, speed-responsive means for controlling the rate and direction of flow through said lastnamed conduit means, and means for driving said speed-responsive means comprising a shaft, a driver connected to drive said shaft, and an element shiftable oppositely to vary oppositely'the speed of rotation of said shaft, said piston being operatively connected to shift said element.

4. In a device of the class described, a fluid reservoir, a fluid pump having an inlet and an outlet, a first conduit connecting said reservoir with said pump inlet, a fluid motor comprising a cylinder 1 and a piston reciprocable therein, a second conduit connecting said pump outlet with one end of said cylinder, a third conduit communicating with the other end of said cylinder, afourth conduit communicating with said reservoir, a driving shaft, a driven shaft, means connecting said driving shaft to drive said driven shaft including an element shiftable oppositely to vary oppositely the speed ratio between said shafts, means connecting said piston to shift said shiftable element, and means operable by said driven shaft for controlling the rate and direction of fluid flow through said conduits, in response to variations in the speed of said driven shaft.

5. The combination with a driving shaft, a driven shaft, and means connecting said driving shaft to drive said driven shaft at variable speeds including an element shiftable oppositely to vary oppositely the speed ratio between said shafts, of a fluid motor including a cylinder and a piston reciprocable therein, said piston being operatively connected to shift said element, means for constantly impressing a predetermined fluid pressure upon one side of said piston, a source of fluid under higher pressure, and valve means effective at times to establish communication between the opposite side of said piston and said source, at other times to establish communication between said opposite side of said piston and exhaust, and at other times to close communication with said opposite side of said piston, said valve means being responsive to the speed of said driven shaft.

'6. A test stand for governor mechanism of the type including a fluid pump and a variablydr'iven element operable in response to speed variations to shift a valve from a position establishing communication between a first port and an exhaust through a position closing both of said ports, to a position establishing communication between the delivery port of said pump and said first port, said stand comprising a driven shaft connectible to drive said variably-driven element, a driving shaft, means connecting said driving shaft to drive said driven shaft including an element shiftable oppositely to vary oppositely the speed of said driven shaft, a stand fluid pump, a fluid motor comprising a cylinder and a piston reciprocable therein, a conduit providing communication between the outlet of said stand fluid pump and one end of said cylinder, a conduit connected to the other end of said cylinder and connectible with said first port of said governor mechanism, and means connecting said piston toshift said shiftable element.

driven element operable" in response 'to speed variations to shift a valve from a position establishing communication between a first L port "and an exhaust through a'position closing both of said ports, toa position establishing communication between the delivery port of said pump and said first port, said'stand comprising a driven shaft connectible to drive said variablydriven element, a driving shaft, means conn'ect- --in-'g's'ai'd'-driving shaft to. drive said driven shaft "including an element shiftable oppositely to vary oppositely the speed of said drivenshafua fluid reservoir, a stand fluid pump having-an inlet and an outlet; a fluid"motor comprisinga cylinder ar1d a piston reciprocable therein, a first conduitmeans-connecting said stand fluid pump inlet with said reservoir, a second conduit means connecting said stand fluid pump outlet with one end of said cylinder, at third conduit means connecting said second conduit means and said stand fluid pump outlet with said reservoir, pressure-responsive flow-controlling means operable to prevent fluid fiow through said third conduit means toward said reservoir at pressures below a predetermined value, a fourth conduit means communicating with the opposite end of said cylinder and connectible with the first port of such'governor mechanism, a fifth conduit means communicatin with said reservoir and connectible with the intake of said governor fluid pump, a sixth conduit means connectible with said governor mechanism exhaust and leading to said reservoir and means connecting said piston to shift said shiftable element.

8. A test stand for governor mechanism of the type including a fluid pump and a variablydriven element operable in response to speed variations to shift a valve from a position establishing communication between a first port and an exhaust through a position closing both of said ports, to a position establishing communication between the delivery port of said pump and said first port, said stand comprising a driven shaft connectible to drive said variably-driven element, a driving shaft, means connecting said driving shaft to drive said driven shaft including an element shiftable oppositely to vary oppositely the speed of said driven shaft, a source of fluid under pressure, a fluid motor comprising a cylinder and a piston reciprocable therein, a first conduit means connected to one end of said cylinder, a second conduit means connected to the opposite end of said cylinder, a third conduit ':.means leading from said source, a fourth con- [duit means connectible to said first port of said r overnor mechanism, valve means associated with said conduit means and shiftable between :a position connecting said first conduit means with said third conduit means and said second conduit means with said fourth conduit means, and a position connecting said first conduit means with said fourth conduit means and said second conduit means with said third conduit means, and means connecting said piston to shift said governor mechanism.

9. A test stand for governor mechanism of the type including a fluid pump and a variably-driven element operable in response to speed variations to shift a valve from a position establishing communication between a first port and an exhaust through a position closing both of said ports, to a position establishing communication between the delivery port of said pump and said first port,

said standcomprising a driven shaft connectible -to;drive said variably-driven element, a driving shaft, means connecting said driving shaft to drive-said driven shaft including an element shiftable oppositely to vary oppositely the speed of said driven shaft, a source of fluidunder pressure, afluid motor comprising acylinder and a piston 'reciprocable therein, a first conduit means connected to oneend of said cylinder, a second to said first port of 'said'governor mechanism,

valve means associated with saidconduit means and shiftable between aposition connectingsaid first conduitmeans with said third conduit means and. said, second conduit, means, with said fourth conduit means, and a position connecting said first conduit means with said fourth conduit means and said second conduit means with said third conduit means, a pressure-responsive exhaust valve in said third conduit means, said valve means being operable to vent said third conduit means only when the pressure therein exceeds the pressure of said source by a predetermined amount, and means connecting said piston to shift said governor mechanism.

10. A test stand for governor mechanism of the type including a fluid pump and a variablydriven element operable in response to speed variations to shift a valve from a position establishing communication between a first port and an exhaust through a position closing both of said ports, to a position establishing communication between the delivery port of said pump and said first port, said stand comprising a driven shaft connectible to drive said variably-driven element, a driving shaft, means connecting said driving shaft to drive said driven shaft including an element shiftable oppositely to vary oppositely the speed of said driven shaft, a source of fluid under pressure, a fluid motor comprising a cylinder and'a piston reciprocable therein, a first conduit means connected to one end of said cylinder, a second conduit means connected to the opposite end of said cylinder, a third conduit means leading from said source, a fourth conduit means connectible to said first port of said governor mechanism, valve means associated with said conduit means and shiftable between a position connecting said first conduit means with said third conduit means and said second conduit means with said fourth conduit means, and a position connecting said first conduit means with said fourth conduit means and said second conduit means with said third conduit means, means independent of said conduit means for supplying fluid under pressure to either end of said cylinder while venting the other end of said cylinder, and means for connecting said piston to shift said governor mechanism.

11. The combination of claim 3 in which the operative connection between said piston and said shiftable element comprises a pivoted lever operatively connected to said shiftable element, and a yoke pivotally connected to said piston and adjustably attachable to said lever at any one of a plurality of points on said lever differently spaced from the pivotal axis of said lever, said cylinder being pivotally mounted to swing about an axis parallel with the pivotal axis of said lever.

12. The combination of claim 3 in which said cylinder is mounted to swing about an axis perpendicular to the line of movement of said piston and in which the operative connection between said piston and said shiftable' element comprises alever mounted for oscillation about an axis parallel with said first-mentioned axis and operatively connected with saidshiftable element, and means connecting said piston with said lever at any one of a plurality of points differently spaced from the axis of oscillation-of said lever.

13. The combination of claim 3 in which said cylinder is mounted to swing about an axis perpendicular to the line of movement of said piston and in which the operative connection between said piston and said shiftable element comprises a lever mounted for oscillation about an axis parallel with said first-mentioned axis and operatively connected with said shiitable element,

said lever having a portion angularly related to its main body and inclined toward said first-mentioned axis, and means connecting said piston with said lever at any one'of a plurality of points on said angularly related portion difierently spaced from the axis of oscillation of said lever.

14; The combination of claim 3 in which said cylinder is mounted to swing about anaxis perpendicular to the line of movement of said piston and in which the operative connection between said piston and said shiftable element comprises a lever mounted for oscillation about an axis parallel with said first-mentioned axis and operatively connected with said shiftable element, a second lever operatively but resiliently connected to said first-mentioned lever, and means connecting said piston with said second lever at any one of a plurality of points difierently spaced from the axis of oscillation of said levers.

IRVIN V, FALK. 

